(1) Field of the Invention
The present invention relates to ceramic-metal joined composite bodies.
(2) Related Art Statement
As illustrated in Japanese patent application Laid-open Nos. 58-223,675 and 61-226,501, conventional ceramic-metal joined composite bodies are each constituted by providing a projection on a ceramic member, and fixing the projection to a recess formed in a metallic member through press shrinkage, or expansion fitting, or brazing.
In many of the bodies, a corner of a bottom of the recess of the metallic member is shaped substantially at a right angle or tapered. Further, even when the bottom corner is rounded, no significance has been attributed to its shape.
However, since conspicuous stress concentration occurs at the bottom corner of the recess of the metallic member due to fitted forces in the case of the conventional ceramic-metal joined composite bodies, cracks occur at the corner of the recess bottom of the metallic member owing to bending fatigue under rotation, which sometimes leads to fracture of the joined composite bodies. Thus, the conventional joined composite bodies having high reliability could not be obtained.